<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  
  <script>

    var names = ["abc", "cba", "nba"]

    // indexOf/lastIndexOf
    // find: 查找元素

    // includes
    // console.log(names.includes("nba"))

    // findIndex: 查找元素的索引
    var findIndex = names.findIndex(function(item, index, arr) {
      return item === "nba"
    })
    // var findIndex = names.findIndex(item => item === "nba")
    console.log(findIndex)

  </script>

</body>
</html>